Gas blast circuit interrupter having conducting orifice means

ABSTRACT

A puffer-type circuit interrupter having a composite orifice member with a restricted inner opening defining a takeover arcing contact. In order to prevent the production of a great quantity of ionized gas the arc length is limited and arc drawn between a pair of separable contact rods within the orifice member is transferred to the takeover arcing contact to cause the extinction of the arc by cross blasting the constant length arcing gap.

United States Patent Balmat et al. 1 Feb. 1,1972

[54] GAS BLAST CIRCUIT INTERRUPTER 3,331,935 7/1967 Milianowicz ..200/150 G HAVING CONDUCTING ORIFICE 3,390,240 6/1968 Circle etal ..200/148 B MEANS 3,527,912 9/1970 Jaillet ..200/148 A [72] Inventors: Georges Balmat, Grenoble; Jean Jailiel, I FOREIGN PATENTS OR APPLICATIONS SamEgreve bmh France 1,207,473 12/1965 Germany ..200/148 A [73] Assignee: Merlin Gerin, Grenoble, France Primary Examiner-Robert S. Macon F l 7 [22] red J ly 13 19 0 Attorney-Stevens, Davrs, M11ler& Mosher 1211 Appl. No.: 54,229

[57] ABSTRACT A, I G, A puffer type circuit interrupter having a composite orifice CI. ..II0lh member a reslricted inner opening defining a takeover hem of Search "200/148 148 B arcing contact. In order to prevent the production of a great quantity of ionized gas the arc length is limited and are drawn [56] References cued between a pair of separable contact rods within the orifice UNn-ED STATES PATENTS member is transferred to the takeover arcing contact to cause the extinction of the are by cross blasting the constant length 3,158,723 11/1964 Buechner ..200/148 A arcing gap 3,160,727 12/1964 Colclaser, Jr. et al .200/144 AP 3,238,340 3/1966 Lerch ..200/148 A 20 Claims, 3 Drawing Figures PATENTEU FEB 1 I972 SHEET 1 OF 3 Fig.1

PATENIEBFEB m2 SHEET 2 [IF 3 Fig.2

PATENIEUFEB H972 SHEET 3 OF 3 Fig.3

GAS BLAST CIRCUIT INTERRUPTER HAVING CONDUCTING ORIFICE MEANS This invention relates to a gas blast circuit interrupter, particularly of the puffer type, comprising orifice means and a pair of separable contact members which can be separated to draw an are within said orifice means, whereby said arc is subsequently extinguished by a blast of arc extinguishing gas through said orifice means.

Circuit interrupters of the puffer type having an orifice of insulating material are widely known. It has been found that in these apparatus having an arc extinction chamber of reduced volume the lengthening of the arc favors the appearance of a very large volume of ionized gas which results in a high pres sure which tends to oppose the flow of fresh arc extinguishing gases which is indispensable for the quenching of the arc.

An object of the present invention is to overcome this drawback and to provide a circuit interrupter having increased arc extinction performances at a given dimension of the are extinction chamber.

It is another object of the invention to provide a puffer-type circuit interrupter having improved arc transfer characteristics.

Still another object of the invention is to provide an orificetype puffer circuit interrupter permitting cross-blasting of the arc.

A further object of the invention is to provide an orificetype circuit interrupter wherein the arc is blasted in a constant length position which is favorable for optimal arc extinction performances.

Another object of the invention is to provide an orifice-type puffer interrupter comprising simple means for automatically inserting a variable resistor in the circuit.

Other advantages and characteristics of the invention will appear from the following description of two embodiments of the invention, given for purposes of illustration only and shown in the accompanying drawings, in which:

FIG. 1 is an axial section through a circuit interrupter in accordance with the invention, shown in closed circuit position.

FIG. 2 corresponds to FIG. 1, but the circuit interrupter is shown during the opening movement thereof.

FIG. 3 illustrates another embodiment of the invention in a position similar to that of FIG. 2.

In FIGS. 1 and 2 an insulating enclosure in the form of a closed housing is formed by a cylinder which is closed at its ends by plates 12 and 14, one of which is traversed by a sliding drive rod 16 the outer portion of which cooperates with a drive device (not shown). A blast piston 18 is arranged for sliding within the cylinder 10 under the action of the rod 16 to the end of which it is fastened. The periphery of the piston has a lip gasket 10 which slides against the inner wall of the cylinder 10 and assures sealing in the direction of displacement ofthe piston 18 which corresponds to the opening movement of the circuit interrupter and is indicated by the arrow F in FIG. 2. In the opposite direction the gasket 20 preferably permits free communication between the two sides of the piston 18. An orifice member 22 is secured to the piston 18 which has orifices 24 which provide communication through the inner portion of the orifice member 22 between the two chambers defined in the cylinder 10 by the piston 18. Inside the orifice member 22 and concentrically to it there is arranged a movable contact 26 which is connected in a telescoping or lost motion manner to the end of the rod 16 so as to be able to carry out a limited axial movement with respect to the latter. For this purpose, a compression spring 28 is inserted between the rod 16 and the movable contact 26 and biases the latter to a position away from the rod 16 in which it is held by a stop 30 cooperating with a collar 32 on the rod 16. A jaw contact member 34 electrically connects the movable contact 26 to the rod 16 which serves as current supply conductor for the movable contact 26.

The upper end 12 of the cylinder 10 supports an opposite terminal 35 of the apparatus which is connected to a stationary contact consisting of a cylindrical rod 36 arranged in the axis of the cylinder l0 opposite the movable contact 26 with which it cooperates. In the closed position of the circuit interrupter as shown in FIG. 1, the contacts 26 and 36 abut against each other and the zone of contact is localized within the orifice member 22 upstreamas seen in the direction of flow of the arc extinction fluid-of a narrowed or restricted section or throat 38. of the orifice member 22. The lost-motion mounting of the contact member 36 can, of course, be applied to the stationary contact 36 and the contacts may be of any other type, for instance of the fitting, penetrating or sliding type.

The upper end I2 further supports a cylindrical tubular sleeve 40 which is coaxial to the cylinder 10 and is connected at its base to the terminal 35. The tubular part 40 consists of conductive material and has orifices 41 near its base. The other end 42 of the tubular part 40 surrounds the orifice member 22 which fits therein with overlap over a suitable distance and cooperates with main contacts 44 which are in the form of jaw elements secured to the piston 18 and electrically connected to the rod 16. Sliding contacts 46 which are secured to tube 40 and slide on the outer surface of orifice member 22 connect the latter electrically to the tube 40 in the closed circuit position. The passage of the rod 16 through the bottom 14 is sealed by bellows 48 or in any other manner.

In the embodiment illustrated in FIG. 1, the orifice member 22 comprises an upper portion 50 of conductive material which extends downstream of the throat and an insulating portion 52 which secures the portion 50 to the piston 18. The conductive portion 50 is electrically connected to a conductive ring 51 on the outside of the insulating portion 52 and the sliding contact members 46 cooperate successively with the ring 51 and the outer surface of the portion 50 to connect the latter electrically during a predetermined opening stroke of the contacts 26 and 36 to the contact 36.

In the closed position of the contacts (see FIG. 1) the electrical continuity between the terminals 16 and 35 is assured by the engaged main contacts 42, 44 and by the engaged arcing contacts 26, 36. The conductive portion 50 of the nozzle 22 is insulated from the movable contact 26 by the portion 52 and connected by the sliding contacts 46 and by the tubular part 40 to the stationary contact 36. The enclosure 10 is advantageously airtight and filled with a quenching fluid, such as compressed sulfur hexafluoride, or another gas or liquid preferably an electronegative gas.

The circuit interrupter of the invention operates in the following manner:

In order to open the circuit interrupter, the drive rod 16 is moved downward in the direction indicated by the arrow F, it carrying along with it the piston 18, the movable main contact 44, the orifice member 22 and the support of the movable arcing contact 26, the latter remaining during an initial phase of the movement in contact with the rod 36 under the action of the spring 28. This displacement brings about, on the one hand, the separation of the main contacts 42, 44 which, shunted by the contacts 26, 36, open without drawing an arc and entail on the other hand, a compression of the fluid in the lower part of the enclosure 10, which works as a puffer cylinder the volume of which decreases with the descending motion of the puffer piston 18. The contacts 46 slide on the conductive portions 50 and 51, maintaining electric continuity between the latter and the contact 36. In a second phase of the opening, the collar 32 of the rod 16 comes against the stop 30 of the arcing contact 26 and carries the latter along with it, causing the opening of the contacts 26, 36 with the formation of an are drawn between the contacts 26, 36 within the orifice 22. Under the effect of the increasing in pressure with the continued displacement of the piston 18, a blast of fluid is produced within the orifice member 22 tending to blow out the arc. As soon as the distance between the contacts 26, 36 reaches a predetermined value, the arc leaves the stationary contact 36 and transfers to the conductive portion 50 of the orifice member 22, which is at the same potential as the stationary contact 36 as a result of the action of the contacts 46 (see FIG. 2). The length of the arc is thus limited and under the effect of the blowing which continues and acts transversely tothe path of the arc, the latter is cross-blasted and extinguished.

During this second phase of the extinction of the arc, the contacts 46 have remained in contact with the orifice member 22, and it is only at the end of the opening stroke and after extinction of the arc that they isolate to improve the dielectric resistance of the arc extinction chamber.

It is easy to see that the length of the arc remains limited to a length which is predetermined by the structural characteristics of the circuit interrupter. The selection of this length or, more precisely, of the minimum distance between the contact 26 and the inner surface of the orifice member 22 in the zone of stagnation of the are results from a compromise between the spark over distance and rate of flow of the quenching gas in this zone. Outstanding results have been obtained with spacings of between 3 and 4 mm., the root of the arc fixing itself in the vicinity of the throat 38 of the orifice member 22. The blast takes place transverse to the arc, assuring rapid deionization. The main contacts 42, 44 outside the orifice member 22 are protected by the latter which forms a screen for the splattering of metal due to the arc. The ionized hot gases are guided by the orifice member 22 and the tubular part 40 which extends it towards the top of the enclosure into a region remote from the main contacts 42, 44 where they escape from the tube 40 through the orifices 41.

In the example which has been more particularly described and shown in FIGS. 1 and 2, the entire upper portion 50 of the orifice member is of conductive material and the electrical connection with the stationary contact 36 is effected by sliding contacts 46. It is'obvious that only a small portion of the orifice member 22 may be conductive and that it can be connected in any other manner, for instance by a wire strap to the stationary contact 36. The device of the invention lends itself particularly well to theinserting in series with the arc of a resistance which favors the interruption of the currents and particularly of inductive currents. In the example shown in FIGS. 1 and 2, this purpose can easily be achieved by using an orifice member 22 of resistive material, such as graphite, and it will be understood that as soon as the arc attaches itself to the orificemember 22, the current passes over a resistant path across the orifice member to reach the slide sliding contacts 46 and the terminal 35. An effect which is beneficial to the extinction of the are results in the increasing of this path and therefore of the inserted resistance during the displacement of the orifice member. The additional resistance can also be inserted in the connection between the terminal 35 and the orifice member 22, as will become more clearly evident below.

Numerous modifications are possible without leaving the scope of the invention and, by way of example, FIG. 3 illustrates an embodiment in which the function of stationary main contact and the function of electrical connection of the orifice member to the stationary contact are dissociated. For reasons of clarity and description, the same reference numbers designate in this figure, parts which are similar or identical to those of FIGS. 1 and 2. The moving main contact 44 cooperates with a stationary contact 54, and the orifice member 22 bears sliding contacts 56 which slide on a tube 58 which connects the orifice member 22 to the terminal 35. The tube 58 and/or the orifice member 22 may be of a material which is a good conductor of electricity, such as copper or steel, or, in the manner described above, of a resistive material in order to insert a resistance in the circuit of the arc. In the case shown in FIG. 3, the increase of the resistance in the circuit corresponds to an increased length of tube 58 in series resulting from the displacement of the sliders 56, but it is obvious that the sliding contacts may be secured to the tube 58 and slide on a resistive orifice member 22 in the manner described above. The tube 58 may comprise a wound resistance, preferably embedded in the tube. The main contacts 44 and 54-are now independent of the orifice member 22.

It should be understood that the invention is in no way limited to the embodiments which have been described and shown by way of example only, but, rather, extends to any variant which does not go beyond the scope of equivalents. By way of example, the orifice member 22 and the mechanically associated contact 26 may be fixed, the opening of the circuit interrupter being effected in this case by displacement of the contact 36 which is electrically connected to the orifice member 22, without the operation'of the apparatus being affected thereby. The puffer piston is then independent of the orifice member and rigidly connected in any desired manner to the moving portion of the unit. The flowing of the blast fluid can be produced in a different manner, for instance by an auxiliary source of compressed fluid.

What is claimed is: v

l. A gas blast circuit interrupter comprising orifice means, a pair of separable contact members extending through said orifice means to draw an arc therein, blast means for forcing a unidirectional blast of gas through said orifice means to cause the extinction of said arc, said orifice means having a conducting inner portion to which an arcmay attach, and connection means for connecting said conducting inner portion electrically to one of said separable contact members at least during a part of the opening movement of said contact members, said conducting inner portion being shaped and positioned relative to said one contact member to cause said are drawn between said contact members to transfer during said opening movement from said one contact member to said conducting inner portion, and support means to support the other contact member in stationary relation with respect to said conducting inner portion upon transfer of said arc so that the length of the transferred arc remains substantially constant within the said orifice means until the extinction thereof by said blast of gas.

2. A circuit interrupter according to claim 1, wherein said connection means comprise further separable contact means isolating said conducting inner portion in response to final opening movement of said one contact member.

3. A gas blast circuit interrupter comprising orifice means, a pair of separable contact members extending through said orifice means to draw an arc therein, blast means for forcing a unidirectional blast of gas through said orifice means to cause the extinction of said are, said orifice means having a conducting inner portion to which an arc may attach, and means for connecting said conducting innerportion electrically to one of said separable contact members at least during a part of the opening movement of said contact members, said connecting means comprising a sliding contact engaging the outer surface of said orifice means and isolating said conducting inner portion in response to a final opening movement of said one contact member, said conducting inner portion being shaped and positioned relative to said one contact member to cause said are drawn between said contact members to transfer from said one contact member to said conducting inner portion, the position of the other contact member relative to said conducting inner portion being such that the length of the transferred arc remains substantially constant until the extinction thereof by said blast of gas.

4. A circuit interrupter according to claim 1, wherein said orifice means comprise a first blast gas guiding orifice member of insulating material surrounding said other contact member and secured to a second orifice member surrounding at least an end portion of said one contact member in the close-circuit position thereof and comprising said conducting inner portion defining a restricted inner opening of conducting material disposed intermediate the end portions of said orifice means.

5. A circuit interrupter according to claim 4, wherein said second orifice member is composed of resistance material and comprises a frustoconical inner surface converging towards said restricted opening and opening towards said one contact member.

6. A circuit interrupter according to claim 1, wherein said connection means comprise a series resistor.

7. A circuit interrupter according to claim 6, wherein said resistor comprises means to be progressively inserted in series by said connection means.

8. A gas blast circuit interrupter comprising orifice means, a pair of separable contact members extending through said orifice means to draw an arc therein, blast means for forcing an unidirectional blast of gas through said orifice means to cause the extinction of said arc, said orifice means having a conducting inner portion to which an arc may attach, and means for connecting said conducting inner portion electrically to one of said separable contact members at least during a part of the opening movement of said contact members, said conducting inner portion being shaped and positioned relative to said one contact member to cause said are drawn between said contact members to transfer from said one contact member to said conducting inner portion, the position of the other contact member relative to said conducting inner portion being such that the length of the transferred arc remains substantially constant until the extinction thereof by said blast of gas, wherein said other contact member comprises a conducting rod secured to said orifice means, a relatively movable arcing contact, and resilient bias means to bias said arcing contact towards the said one contact member, whereby said arcing contact is attached by a lost motion connected to said rod.

9. A circuit interrupter according to claim 8, wherein said conducting inner portion comprises a restricted portion to which the transferred arc may attach and which is positioned a short distance from said arcing contact in the extended position thereof.

10. A circuit interrupter according to claim 1, wherein said blast means comprise a puffer cylinder cooperating with a perforated piston, said piston being secured to said orifice means.

11. A circuit breaker according to claim 1, wherein said orifice means is at least partly composed of resistance material.

12. A puffer-type circuit interrupter comprising movable orifice means having a restricted inner opening defined by an inner wall portion of conductive material, a relatively stationary puffer cylinder, a perforated piston movable in said cylinder and secured to said orifice means to establish a blast of gas through said opening, separable contact means defining in the closed circuit position thereof a current path extending through said opening and comprising a relatively stationary contact member and a movable contact member, said contact members having confronting arcing end portions to draw an arc therebetween within said orifice means, and connection means for connecting said inner wall portion electrically to said relatively stationary contact member during at least a part of the opening movement of said contact means, said inner wall portion and said arcing end portion of said movable contact member being shaped and positioned so as to cause said arc drawn between said arcing end portions to transfer from said relatively stationary contact member to said inner wall portion during said opening movement, whereby said inner opening and said arcing end portion of said movable contact are spaced apart a small substantial constant distance after separation of said contact means to cause blast of gas to extinguish said are of substantially constant length.

13. A circuit interrupter according to claim 12, wherein said orifice means is composed of a first orifice member of conductive material including said inner wall portion and a second orifice member of insulating material for guiding of said blast of gas and for supporting said first orifice member from said piston.

14. A circuit interrupter according to claim 12, wherein said movable contact member comprises a relatively movable arcing end portion, resilient bias means to bias said arcing end portion of said movable contact member towards said relatively stationary contact member, and stop means to limit the relative movement of said arcing end portion in the direction of said relatively stationary contact member so that said arcing end portion in the extended end position thereof defines with said inner wall portion cross blast arcing gap.

15. A circuit interrupter according to claim 12, wherein said puffer cylinder constitutes a gastight enclosure housing said contact means, said piston and said orifice means and containinga compressed gas of high arc-extinguishing power.

6. A circuit interrupter according to c mm 12, further comprising a pair of main contacts including an annular relatively stationary main contact surrounding said orifice means at least partially in the closed circuit position of the circuit interrupter.

17. A circuit interrupter according to claim 16, wherein said pair of main contacts comprise at least one movable main contact supported by said piston and cooperating with said relatively stationary main contact,

18. A circuit interrupter according to claim 12, wherein said orifice means is at least partially composed of resistance material.

19. A circuit interrupter according to claim 12, wherein said connection means comprise sliding contact means cooperating with a series resistor.

20. A puffer-type circuit interrupter comprising orifice means having a restricted inner opening defining a takeover arcing contact, a pair of separable contact members to draw an arc within said orifice means, means to connect said takeover arcing contact electrically to one of said contact members, during at least a part of the opening movement of said contact members, said takeover arcing contact and said contact members being shaped and being positioned during said opening movement to cause said are to extend across a substantially constant length arcing gap defined by said takeover arcing contact and the other contact member therebetween, and puffer means to establish through said arcing gap a cross blast of compressed gas guided by said orifice means. 

1. A gas blast circuit interrupter comprising orifice means, a pair of separable contact members extending through said orifice means to draw an arc therein, blast means for forcing a unidirectional blast of gas through said orifice means to cause the extinction of said arc, said orifice means having a conducting inner portion to which an arc may attach, and connection means for connecting said conducting inner portion electrically to one of said separable contact members at least during a part of the opening movement of said contact members, said conducting inner portion being shaped and positioned relative to said one contact member to cause said arc drawn between said contact members to transfer during said opening movement from said one contact member to said conducting inner portion, and support means to support the other contact member in stationary relation with respect to said conducting inner portion upon transfer of said arc so that the length of the transferred arc remains substantially constant within the said orifice means until the extinction thereof by said blast of gas.
 2. A circuit interrupter according to claim 1, wherein said connection means comprise further separable contact means isolating said conducting inner portion in response to final opening movement of said one contact membEr.
 3. A gas blast circuit interrupter comprising orifice means, a pair of separable contact members extending through said orifice means to draw an arc therein, blast means for forcing a unidirectional blast of gas through said orifice means to cause the extinction of said arc, said orifice means having a conducting inner portion to which an arc may attach, and means for connecting said conducting inner portion electrically to one of said separable contact members at least during a part of the opening movement of said contact members, said connecting means comprising a sliding contact engaging the outer surface of said orifice means and isolating said conducting inner portion in response to a final opening movement of said one contact member, said conducting inner portion being shaped and positioned relative to said one contact member to cause said arc drawn between said contact members to transfer from said one contact member to said conducting inner portion, the position of the other contact member relative to said conducting inner portion being such that the length of the transferred arc remains substantially constant until the extinction thereof by said blast of gas.
 4. A circuit interrupter according to claim 1, wherein said orifice means comprise a first blast gas guiding orifice member of insulating material surrounding said other contact member and secured to a second orifice member surrounding at least an end portion of said one contact member in the close-circuit position thereof and comprising said conducting inner portion defining a restricted inner opening of conducting material disposed intermediate the end portions of said orifice means.
 5. A circuit interrupter according to claim 4, wherein said second orifice member is composed of resistance material and comprises a frustoconical inner surface converging towards said restricted opening and opening towards said one contact member.
 6. A circuit interrupter according to claim 1, wherein said connection means comprise a series resistor.
 7. A circuit interrupter according to claim 6, wherein said resistor comprises means to be progressively inserted in series by said connection means.
 8. A gas blast circuit interrupter comprising orifice means, a pair of separable contact members extending through said orifice means to draw an arc therein, blast means for forcing an unidirectional blast of gas through said orifice means to cause the extinction of said arc, said orifice means having a conducting inner portion to which an arc may attach, and means for connecting said conducting inner portion electrically to one of said separable contact members at least during a part of the opening movement of said contact members, said conducting inner portion being shaped and positioned relative to said one contact member to cause said arc drawn between said contact members to transfer from said one contact member to said conducting inner portion, the position of the other contact member relative to said conducting inner portion being such that the length of the transferred arc remains substantially constant until the extinction thereof by said blast of gas, wherein said other contact member comprises a conducting rod secured to said orifice means, a relatively movable arcing contact, and resilient bias means to bias said arcing contact towards the said one contact member, whereby said arcing contact is attached by a lost motion connected to said rod.
 9. A circuit interrupter according to claim 8, wherein said conducting inner portion comprises a restricted portion to which the transferred arc may attach and which is positioned a short distance from said arcing contact in the extended position thereof.
 10. A circuit interrupter according to claim 1, wherein said blast means comprise a puffer cylinder cooperating with a perforated piston, said piston being secured to said orifice means.
 11. A circuit breaker according to claim 1, wherein said orifice means is at least partly Composed of resistance material.
 12. A puffer-type circuit interrupter comprising movable orifice means having a restricted inner opening defined by an inner wall portion of conductive material, a relatively stationary puffer cylinder, a perforated piston movable in said cylinder and secured to said orifice means to establish a blast of gas through said opening, separable contact means defining in the closed circuit position thereof a current path extending through said opening and comprising a relatively stationary contact member and a movable contact member, said contact members having confronting arcing end portions to draw an arc therebetween within said orifice means, and connection means for connecting said inner wall portion electrically to said relatively stationary contact member during at least a part of the opening movement of said contact means, said inner wall portion and said arcing end portion of said movable contact member being shaped and positioned so as to cause said arc drawn between said arcing end portions to transfer from said relatively stationary contact member to said inner wall portion during said opening movement, whereby said inner opening and said arcing end portion of said movable contact are spaced apart a small substantial constant distance after separation of said contact means to cause blast of gas to extinguish said arc of substantially constant length.
 13. A circuit interrupter according to claim 12, wherein said orifice means is composed of a first orifice member of conductive material including said inner wall portion and a second orifice member of insulating material for guiding of said blast of gas and for supporting said first orifice member from said piston.
 14. A circuit interrupter according to claim 12, wherein said movable contact member comprises a relatively movable arcing end portion, resilient bias means to bias said arcing end portion of said movable contact member towards said relatively stationary contact member, and stop means to limit the relative movement of said arcing end portion in the direction of said relatively stationary contact member so that said arcing end portion in the extended end position thereof defines with said inner wall portion cross blast arcing gap.
 15. A circuit interrupter according to claim 12, wherein said puffer cylinder constitutes a gastight enclosure housing said contact means, said piston and said orifice means and containing a compressed gas of high arc-extinguishing power.
 16. A circuit interrupter according to claim 12, further comprising a pair of main contacts including an annular relatively stationary main contact surrounding said orifice means at least partially in the closed circuit position of the circuit interrupter.
 17. A circuit interrupter according to claim 16, wherein said pair of main contacts comprise at least one movable main contact supported by said piston and cooperating with said relatively stationary main contact.
 18. A circuit interrupter according to claim 12, wherein said orifice means is at least partially composed of resistance material.
 19. A circuit interrupter according to claim 12, wherein said connection means comprise sliding contact means cooperating with a series resistor.
 20. A puffer-type circuit interrupter comprising orifice means having a restricted inner opening defining a takeover arcing contact, a pair of separable contact members to draw an arc within said orifice means, means to connect said takeover arcing contact electrically to one of said contact members, during at least a part of the opening movement of said contact members, said takeover arcing contact and said contact members being shaped and being positioned during said opening movement to cause said arc to extend across a substantially constant length arcing gap defined by said takeover arcing contact and the other contact member therebetween, and puffer means to establish through said arcing gap a cross blast of compressed gas guided by said orifice means. > 